OBJECTIVE 5: THE STUDENT WILL DEMONSTRATE AN UNDERSTANDING OF MOTION, FORCES, AND ENERGY. Basic Physics

Knows concepts of force and motion evident in everyday life. Motion and Forces

 Calculate speed, momentum, acceleration, work, and power in systems such as in the human body, moving toys, and machines.  Investigate and describe applications of Newton's laws such as in vehicle restraints, sports activities, geological processes, and satellite orbits.  Investigate and demonstrate [mechanical advantage and] efficiency of various machines such as levers, motors, wheels and axles, pulleys, and ramps.

Equations  There are many equations you need to know how to use.  You will get a formula sheet with constants. Be sure you know how to use it and are familiar with it.

Speed and Velocity  How fast you change your position.  Units: t’s up.  Speed & velocity: m/s or cm/s or km/hr  Distance: m or cm or km  Time: seconds (s) or hours (h)

Acceleration  Acceleration is the rate of change of velocity.  It occurs when an object changes its speed, its direction or both.  Units:  Acceleration: m/s/s or m/s 2  Velocity: m/s  Time: s

Force  Force is a push or pull that makes things move (accelerate). This is Newton’s second law and the force is the net force.  Units:  Force: Newtons (N) sometimes (n)  Mass: kg  Acceleration: m/s/s or m/s 2

Newton’s First law of Motion  An object in motion will stay in motion and an object at rest will stay at rest unless acted upon by an external force.  A body persists in a state of uniform motion or of rest unless acted upon by an external force.  A body keeps doing what its doing unless forced to change.  AKA: the law of inertia.

Newton’s Second Law of Motion:  Force = mass x acceleration (this is a formula)  Force equals mass times acceleration.  net F = ma (formula sheet)  AKA: F = ma  With equal force…  a smaller mass object will accelerate at a large rate  a big mass will accelerate at a small rate.  With equal masses…  a larger force will accelerate it at a faster rate  a small force will accelerate it at a smaller rate.

Weight  You use Newton’s second law to calculate something’s weight.  The acceleration you would use is the acceleration due to gravity; 9.8 m/s/s This is given to you on the formula sheet. Weight = mass (in kilograms) x 9.8 m/s/s  Your weight would be in Newtons (N)

Newton’s Third Law of Motion:  For every action there is an equal and opposite reaction.  AKA: Action – Reaction Law  Action – Reaction Pairs.  Action: Joe hits Jack Reaction: Jack hits Joe  Action: Bob pulls on box Reaction: Box pulls on Bob  Action: Earth pulls on Moon Reaction: Moon Pulls on Earth

Gravity  The pull of gravity depends on the size of the objects (masses) and the distance between their centers.  This is explained by Newton’s Universal Law of Gravity. There is gravity between all objects in the universe.  Increasing the masses of one or both objects increases the force between them.  Increasing the distance between their centers, decreases the force of gravity (by a square).

Gravity and Circles  Objects travel in a circle because something holds it in orbit.  This force is the pull of gravity.  It is caused by the two objects in question and the distance between them.  The pull of gravity is everywhere.

Momentum, p  Momentum is moving mass.  Momentum is mass times its velocity.  Momentum, p, is measured in either:  kg m/s or g cm /s  There is a formula for momentum.

Momentum  Momentum is a concept of moving mass.  Units:  Momentum: kg m/s or g cm/s  Mass: kilograms (kg) or grams (g)  Velocity: m/s or cm/s

Conservation of Momentum  The total momentum before equals the total momentum after.  In dealing with momentum, directions matter.

Conservation of Momentum  The total momentum before a happening or collision equals the total momentum after.  You find the mv of each object before a collision and the mv of each object after and they must be equal.  Momentum is a vector so its direction matters. The direction of the momentum is the same direction as its velocity.  They like momentum problems.

Knows the impact of energy transformations in everyday life. Energy

 Describe the law of conservation of energy.  Investigate and demonstrate the movement of heat through solids, liquids, and gases by convection, conduction, and radiation.  Investigate and compare economic and environmental impacts of using various energy sources such as rechargeable or disposable batteries and solar cells.

Convection  A form of heat transfer through liquids and gases (fluids).  Heat is transferred by currents in the fluids.  Heat moved by fluid motion.

Conduction  Heat transferred by vibrating neighboring molecules.  Heat transferred through solids.  Heat moves from hot to cold.

Radiation  Heat transferred by waves.  Heat from our Sun reaches us through waves.

Work, W  Work is defined as force acting over a distance.  The force must move the object.  There is a formula for work.  Work, W, is measured in Joules, J.

Work  Work is force acting over a distance. The force must move the object.  Units:  Work Joules (J) sometimes (j)  Force: N  Distance: m

Kinetic Energy  Energy of motion.  If an object is moving it has kinetic energy.  There is a formula for kinetic energy.  Energy is measured in Joules, J.

Kinetic Energy  Energy due to motion.  Units:  KE: Joules (J)  Mass: kg  Velocity: m/s

Potential Energy  Potential energy is stored energy.  For TAKS, It is energy due to an object’s height.  There is a formula for potential energy.  Energy is measured in Joules, J.  Changes in potential energies are important.

Gravitational Potential Energy  Energy due to its position and the pull of gravity.  Units:  PE: Joules (J)  Mass: kg  Acceleration due to gravity: 9.8 m/s/s  Height: m

Conservation of Energy  The total energy before equals the total energy after.  Energy can change forms.  Work is a form of energy.

Conservation of Energy  Energy must be accounted for.  Energy can change forms from Potential Energy to Kinetic Energy and back again. The total amount of energy a system can have can change by doing work in the system.  The total energy of a system equals a constant.  Energy can be lost to: Work done by friction and lost to heat.  KE + PE at one place = KE + PE at another place

Power; Mechanical  Power is how fast work is done or how fast energy is generated or used up (dissipated).  Units: t’s up.  Power: Watts (W) or kiloWatts kW  Work: J  Time: s

Machines  A machine is a device that takes work (force x distance) and increases the applied force by decreasing the distance. It’s a trade off. You always need more input work than you get out because some work goes to overcome friction and heat.  There is no such thing as a 100% efficient machine.  You never get out more than you put in.  Simple machines  Lever  Pulley  Screw  Inclined plane  Wedge  Wheel and Axle

Which lever would require the least effort to lift the box ? A C B D

Levers load distance distance force fulcrum or pivot If in balance: load x distance = distance x force

Efficiency: Machines  A percentage of how much work you do goes into doing the job.  Units:  Efficiency is a %, no units  Work: J

The 6 Simple Machines

Energy - Mass  This is the connection between mass and energy. Einstein’s equation.  Units:  Energy: Joules (J)  Mass: kg  c = 3 x 10 8 m/s

Knows the effects of waves on everyday life. Waves

 Demonstrate wave interactions including interference, polarization, reflection, refraction, and resonance within various materials.

Wave  A wave is a disturbance (energy) carried through a material medium. (mechanical wave)  Light is an electromagnetic wave. It does not need a material medium to travel through.  There are two types of mechanical waves:  Transverse waves are made perpendicular to the medium.  Longitudinal waves are made parallel to the medium.

Wave Equation  This is the equation you use with waves.  Units:  Velocity: m/s  Frequency: Hertz (Hz)  Wavelength: m

Wave Parts

Frequency, f  Frequency, f, is how many things happen in one second.  How many waves are made in 1 second.  Frequency, f, is measured in Hertz, Hz.

Period, T  The amount of time it takes to do something once.  The amount of time to make one wave.  Period, T, is measured in seconds, s.

Wavelength, λ  The length of one wave is called the wavelength.  It’s the distance from crest to crest, trough to trough, or from corresponding part to like corresponding part.  Wavelength, λ, is.measured in meters, m

Amplitude  The height of a wave from equilibrium, or the depth of the wave from equilibrium.  Amplitude is usually measured in meters, m.

Medium  The stuff that carries the wave.  Sound travels in air.  Water waves travel in water.  Earth quakes travel in dirt (earth)  Light travels in empty space (light is an electromagnetic wave and does not need a medium)

Wave Properties

Reflection  When a wave hits a barrier it bounces off at the same angle it hits the surface.  When you look in the mirror you see your reflection.  The law of reflection is the angle of the incoming ray equals the angle of the out going ray.

Refraction  When a light ray changes mediums it bends. The bending of alight ray is refraction.  When a wave changes mediums it refracts.  The change of direction of a ray of light, sound, heat, or the like in passing from one medium into another due to the change in the speed of the wave.

Diffraction  The change in a wave as it passes by an obstacle or through an opening.  The spreading out of a wave as it passes by a barrier.

Resonance  Also called sympathetic vibrations.  Something starts to vibrate or shake because something else is vibrating.

Sound  Sound is a longitudinal wave.  It travels at around 340 m/s (constants chart)  The note or pitch of a sound wave is its frequency.  The loudness of the sound wave is its amplitude.  Sound needs a medium to travel through, this medium is air.  Sound are waves that our ears can pick up.

Light  Light is a transverse wave. It is also an electromagnetic wave.  Light does not need a medium to travel through.  It travels at a maximum speed of 3 x 10 8 m/s, the speed of light (constants chart)  This speed is also called c.  White light has all the colors in the rainbow.  Roy G Biv.

Light  The primary colors of light are Red, Green, & Blue. RGB  Light colors are different frequencies (or wavelengths) of light.  Light we see is called the visible spectrum.  Light wavelengths are very small.

Electricity

Electric Circuits  An electric circuit has three basic parts:  A source of electricity : a battery or outlet (voltage)  Connectors that carry the electricity in a closed loop; wires  Objects that use electricity, resistors, light bulbs, etc.  The devices that use electricity and be connected:  In series, one after the other.  In parallel, there are multiple pathways (loops)  There must be a closed loop from one end (+ pole) of the battery to the other end ( − pole)

Series Circuits  When a circuit is connected in series;  The electrons coming out of the battery must pass through each device.  If the pathway is broken, all devices stop working.  The voltage is divided up with each device in the circuit.  The current (amps) is the same throughout the circuit.

Series Circuits

Parallel Circuits  When a circuit is connected in parallel:  There are multiple pathways for electricity to travel.  Each device gets the same voltage, equal to the voltage of the battery.  The current coming out of the battery divides and takes separate paths to the other side of the battery.  If one device goes out, the rest can stay on.  Most Christmas lights are connected in parallel.  Houses are wired in parallel.

Parallel Circuits

Electrical  Current (I), Voltage (V), Resistance (R) R’s up.  Units  Current: Amperes (A)  Voltage: Volts (V)  Resistance: Ohms (  )

Ohms Law Applied

Electrical Power  How fast electricity is used (dissipated) or made (generated)  Units:  Power: Watts (W)  Voltage: Volts (V)  Current: Amperes (A)

Electrical Energy  Energy due to electricity  Units:  Energy: Joules (J)  Power: Watts (W)  Time: s

You must account for everything. The before equals the after. Conservation Laws

Conservation of Mass  The total mass before equals the total mass after.  Mass cannot be created or destroyed.

Conservation of Momentum  The total momentum before equals the total momentum after.  In dealing with momentum, directions matter.

Conservation of Energy  The total energy before equals the total energy after.  Energy can change forms.  Work is a form of energy.

Units:  Length or distance (d):  meters m  kilometers km  centimeters cm  millimetersmm

Density  How much stuff is crammed into a volume. How much mass is in a confined space.  Units: V’s up.  Density: g/cm 3 g/mL kg/m 3 kg/L  Mass: grams (g) kilograms (kg)  Volume: liters (L) milliLiters (mL) cubic meters (m 3 ) cubic centimeters (cm 3 )

Heat  Heat gained or lost. Heat is a form of energy.  Units:  Heat: calories (cal) Calorie (Cal) kilocalorie (kcal)  Mass: grams (g) or kilograms (kg)  Temperature: Celsius or centigrade (°C)  Specific heat: should be given

Units:  Time (t)  seconds s  hours h  minutes min  Mass (m)  kilogramskg  gramsg

Units:  Volume (V)  Solid:  cubic meters m 3  cubic centimeter cm 3  Liquids:  litersL ; l  millilitersmL ; ml

Units:  Force (F)  Newtons N  Work (W); Energy (E), (KE) and (PE)  Joules J  Power (P)  Watts W  kilowattskW

Units:  Frequency (f)  HertzHz  Electricity  Voltage (V) Volts V  Current (I)Amperes ; Amps A  Resistance (R) Ohms 

Units:  Density (D) mass per volume  kg/m 3 g/cm 3 kg/L g/mL  Velocity (v) speed distance per time  m/s km/h cm/s  Acceleration (a) distance per time per time  m/s/s m/s 2 cm/s/s cm/s 2

Units:  Momentum (p) mass times velocity  kg m/s g m/s g cm/s  Work (W) Force times distance  N m J  Power (P) Work per time  N m/s J/s W

Units:  Heat (Q)  calories cal  JoulesJ  Acceleration due to gravity (g)  9.8 m/s 2